Recently there has been a large demand to improve vehicle fuel consumption in view of resource savings and environmental pollution. It is desirable to reduce the weight of automobile parts, particularly wheel bearing apparatus, to achieve the demand for fuel consumption. Such a demand to reduce the weight of parts has increased, especially, in small sized cars such as light weight 4-wheel cars. Thus, various proposals relating to the wheel bearing apparatus to reduce their weight have been proposed. On the other hand, it is also important to improve the reliability and durability of the wheel bearing apparatus although it is antinomic to the reduction of its weight.
FIG. 4 shows one example of a vehicle wheel bearing apparatus used in a vehicle intended to reduce its weight. The wheel bearing apparatus 52 has a representative structure used for a driven wheel. It includes an inner member 53 including a wheel hub 51, an inner ring 60 press-fit onto the wheel hub 51, an outer member 54, and double row balls 55, 55. The double row balls 55, 55 are contained between the inner and outer members 53, 54. In the descriptions below, the term “outer side” defines a side that is positioned on the outer side of a vehicle body (left-hand side of FIG. 4) and the term “inner side” defines a side that is positioned on the inner side of the vehicle body (right-hand side of FIG. 4) when the wheel bearing apparatus is mounted on the vehicle body.
The wheel hub 51 is integrally formed with four separated wheel mounting flanges 56 (hereinafter referred to as “wheel mounting arms”). The flange 56 radially extends at the wheel hub outer side end. Hub bolts 56a, to fasten a wheel, are secured on the wheel mounting arms 56 equidistantly on one virtual circle. As shown in FIG. 5, each wheel mounting arm 56 is formed so that it radially projects from a brake pilot portion 64. The mounting arm 56 has substantially the same width as a portion where a through aperture 56b for the hub bolt is formed, except a portion near the hub bolt through aperture 56b. 
Further as shown in FIG. 4, a rib 56c is formed on the inner side of the wheel mounting arms 56. The ribs 56c have a gradually increasing wall thickness toward their bases. The wheel hub 51 is formed on its outer circumference with an outer side inner raceway surface 51a. The wheel hub 51 has a cylindrical portion 57 that axially extends from the inner raceway surface 51a. The inner ring 60 is press-fit onto the cylindrical portion 57, via a predetermined interference. The inner ring 60 is formed with an inner side inner raceway surface 60a on its outer circumference. The inner ring 60 is axially secured on the cylindrical portion 57 by a caulked portion 58 that is formed by plastically deforming an end portion of the cylindrical portion 57 of the wheel hub 51.
The outer member 54 is formed with double row outer raceway surfaces 54a, 54a on its inner circumference. The double row balls 55, 55 are rollably contained and held by cages 59 between the mutually opposed outer and inner raceway surfaces 54a, 54a and 51a, 60a. 
A seal 61 is mounted on the outer side end of the outer member 54 to seal an annular space formed between the outer member 54 and the inner member 53. A cup shaped sealing cap (not shown) is mounted on the inner side end portion of the outer member 54 to close an opening of the outer member 54. The seal 61 and sealing cap prevent leakage of lubricating grease sealed in the bearing apparatus. Additionally, the seal prevents entry of rainwater and dusts etc. into the inside of the bearing apparatus.
The outer member 54 is integrally formed with a body mounting flange 54b. The body mounting flange 54b is mounted on a knuckle (not shown) forming part of a suspension apparatus. A plurality of bolts apertures 62 is formed on the outer end of the body mounting flange 54b. As shown in FIG. 5, the body mounting flange 54b is formed with a plurality of radially projected partial flanges 63 separated in a circumferential direction only in portions where the bolt apertures 62 are formed. The inner side end of the outer member 54 is formed with a cylindrical knuckle pilot portion 54c. The pilot portion 54c axially extends from the body mounting flange 54b. A knuckle (not shown) is adapted to be fit onto the outer circumference of the knuckle pilot portion 54c. 
The base of the wheel mounting arms 56 of the wheel hub 51 is formed with a cylindrical brake pilot portion 64. The brake pilot portion 64 extends toward the outer side and is adapted to guide an inner circumference of the brake rotor 65. Wheel pilot portions 66 are also formed on the wheel hub 51. The wheel pilot portions 66 extend from the brake pilot portion 64 toward the outer side. The wheel pilot portions 66 are intended to guide the inner circumference of a wheel 67 to be mounted on the wheel hub 51 being overlapped with the brake rotor 65. The wheel pilot portions 66 are formed with an outer diameter slightly smaller than that of the brake pilot portion 64.
A plurality of notches is formed on the wheel pilot portions 66 in their circumferential direction as discontinuous projections. These discontinuous wheel pilot portions 66 are formed equidistantly in the circumferential direction between adjacent wheel mounting arms 56. This reduces the weight of the wheel hub 51 and enables a relatively uniform thickness in the circumferential direction of the annular base of the wheel mounting arm 56. Thus, this improves the workability during forging of the wheel hub due to easy plastic flow attained in the forged material. Accordingly, it is possible to improve the forging accuracy and productivity of the article. Thus, this reduces the manufacturing cost. Patent Document 1: Japanese Laid-open Patent Publication No. 297925/2005
However, in the prior art wheel bearing apparatus, since they are forged with the plurality of notches in the circumferential direction of the wheel pilot portions 66, cutting burrs 68 (shown by hatching in FIG. 6(a)) tends to be easily generated during a lathe cutting process after forging. This is due to discontinuous cutting (shown by dotted line) of an end 66a. The generated burrs 68 are be bit between reference surfaces during machining processes or between mounting surfaces of the brake rotor 65 and the wheel 67 and cause inaccuracy during machining or mounting.
The generated burrs 68 will be removed by forming chamfered portions 69 on a corner of each wheel pilot portion 66 where the burrs are generated. However, the chamfered portion 69 cannot be formed by lathe cutting and should be formed by applying a cutting tool onto the burred corner of the wheel pilot portion 66. The tool is reciprocated in a radial direction. This is very cumbersome and thus increase the manufacturing cost of the wheel bearing apparatus.
It is also desirable to reduce material loss wasted by cutting and to efficiently and effectively use the material blank.